The invention relates to the technologies for treating atrial fibrillation (AF), and in particular, to methods for determining nature of the atrial substrate and localizing critical regions in atrial fibrillation.
Atrial fibrillation is the most common type of tachyarrhythmia encountered in clinical practice. Catheter ablation is currently the standard therapy in patients who were refractory to antiarrhythmic medication. Pulmonary vein isolation (PVI) has become the mainstream catheter ablation technique for paroxysmal AF. For patients who have not responded to PVI, substrate modification with complex fractionated electrogram (CFE) ablation is considered to be necessary to treat persistent AF.
Conventional AF identification methods include dominant frequency (DF) analyses in frequency domain of consecutive electrograms, and CFE mean analysis in time domain of consecutive electrograms. Both methods produce average results based on activation intervals, which not applicable to diagnosing persistent or late stage AF patients. In particular, CFEs are usually observed in many regions of the atria, which make it difficult to identify critical atrial substrate using the conventional AF identification methods.
Recent clinical and animal studies have demonstrated that AF reentrant sources may be related to rotors, and the degree of electrogram similarity in the waveform propagating from the focal point can be an indicator for identifying the rotors.
For substrate mapping of AF, there is therefore a need to more accurate identification of critical regions and discriminate them from by-standers than conventional AF identification methods, especially, for accurate identification of rotor regions in persistent AF and facilitating electrophysiologist to search for the critical atrial substrate in maintaining AF.